Resizable Bar incompatibilities - whos fault is it?

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ZodaEX

Supreme [H]ardness
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Resizable bar has compatibility issues across vendors. AMD cards only do rebar on AMD chipsets and Nvidia/Intel cards only do rebar on Intel chipsets.
But who is at fault here for it not being universally compatible across all vendor's products? Is this Intel and Nvidia scratching each other's back, or is AMD also locking out Intel and Nvidia cards from using rebar on their platforms?
 
ZodaEX said:
Resizable bar has compatibility issues across vendors. AMD cards only do rebar on AMD chipsets and Nvidia/Intel cards only do rebar on Intel chipsets.
But who is at fault here for it not being universally compatible across all vendor's products? Is this Intel and Nvidia scratching each other's back, or is AMD also locking out Intel and Nvidia cards from using rebar on their platforms?
Click to expand...
I wasnt aware that this is an issue? According to Nvidia at least, they support both AMD and Intel chipsets. :)

https://www.nvidia.com/en-us/geforce/news/geforce-rtx-30-series-resizable-bar-support/
 
ZodaEX said:
Resizable bar has compatibility issues across vendors. AMD cards only do rebar on AMD chipsets and Nvidia/Intel cards only do rebar on Intel chipsets.
But who is at fault here for it not being universally compatible across all vendor's products? Is this Intel and Nvidia scratching each other's back, or is AMD also locking out Intel and Nvidia cards from using rebar on their platforms?
Click to expand...
AMD cards do rebar on Intel chipsets just fine. In fact....it seems to work a little better.


Nvidia seems to have more/less dropped development of resizable bar. It only works in games which have been white listed by their drivers----and they haven't really white listed many games.
 
vegeta535 said:
What you going on about? There is no issues with resizable bar. Been working fine with my x570 and 3080ti. Now the games that support it is very lacking ATM.
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Compatibility issues with resizable bar.
 
intels fault, its always intels fault. ;)
only issue i know of is with the arc cards running like trash without it.
 
I know that there is something that needs to be changed about Windows boot up mode, before it will allow you to use SAM in Windows even if you have the right cpu and video card on says my x470, I did it once with the RX 5700 to get it working, but somehow running a RTX 3070 on that system broke it and now I can't remember how it was done.
 
pendragon1 said:
intels fault, its always intels fault. ;)
only issue i know of is with the arc cards running like trash without it.
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Good! Intel didn't implement legacy/trash mode. If you actually think about what it does "resizeable bar" should have been standard years ago, long before 2020. All it does is map all the GPU's memory into the CPU's address space at once. It should have been standard on a 64-bit OS years ago. So I fully support Intel "forcing" you to enable it. Mapping all of the GPU's memory into the CPU's address space instead of using a silly little window like we're running DOS and using expanded memory is the correct way to do things.

That said I'm sure there are mainboards and vid cards with bugs out there that break things and result in better performance with resizeable bar turned off.
 
I finally have rebar on (Sam) with the x470/ 3700x and RX6600, not sure if it helps or not because no one really tested the older boards.
 
crazycrave said:
I finally have rebar on (Sam) with the x470/ 3700x and RX6600, not sure if it helps or not because no one really tested the older boards.
Click to expand...

I did some benches on my x570/5950/6700 setup. Saw maybe an 8% improvement on the games I tested.
 
I'm using Rebar on my system. 5950X, x570 and a 3080 12GB

Well, I have it enabled. I've checked to make sure it's enabled, but I honestly don't know if it's actually caused any performance improvement anywhere. Maybe a minor improvement in Cyberpunk 2077?
 
ZodaEX said:
Resizable bar has compatibility issues across vendors. AMD cards only do rebar on AMD chipsets and Nvidia/Intel cards only do rebar on Intel chipsets.
But who is at fault here for it not being universally compatible across all vendor's products? Is this Intel and Nvidia scratching each other's back, or is AMD also locking out Intel and Nvidia cards from using rebar on their platforms?
Click to expand...
Citation needed. I've tested resizable bar on AMD and Intel based chipsets and CPUs with a mixture of NVIDIA and AMD cards without issue.
 
ZodaEX said:
Resizable bar has compatibility issues across vendors. AMD cards only do rebar on AMD chipsets and Nvidia/Intel cards only do rebar on Intel chipsets.
But who is at fault here for it not being universally compatible across all vendor's products? Is this Intel and Nvidia scratching each other's back, or is AMD also locking out Intel and Nvidia cards from using rebar on their platforms?
Click to expand...
I have rBAR on ryzen 2700x and b450m board, in the bios you need to turn ON ABOVE 4G DECODING and then you get the option Res.BAR to turn ON
I have Nvidia rtx 3060.

if I had amd gpu then I wouldn't have amd SAM because the processor doesn't support it, I wouldn't have either SAM or BAR.
So I wouldn't have anything until I bought a processor that supports SAM and the gpu rtx 6000 series.
 
b1rd said:
I have rBAR on ryzen 2700x and b450m board, in the bios you need to turn ON ABOVE 4G DECODING and then you get the option Res.BAR to turn ON
I have Nvidia rtx 3060.

if I had amd gpu then I wouldn't have amd SAM because the processor doesn't support it, I wouldn't have either SAM or BAR.
So I wouldn't have anything until I bought a processor that supports SAM and the gpu rtx 6000 series.
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I think the Ryzen 3 3100 was the base line for cpu support with SAM, b350 and x370 should work with update bios flash for Ryzen 3000, I had to switch to secure boot to get SAM to work, doesn't matter if you turn ON ABOVE 4G DECODING = I am also on Windows 11 with it like that.

Seems in Hardware Unboxed review, the 3950x/ RX6600 made some magic happen, but I think he used the x570 board and not an older one, more people would be paired with b450/x470 and a Ryzen 3000 cpu I would think, and as to blow their money on a new gpu upgrade like the RX 6600.

I have it on in Sniper Elite 5 with RX 6600 and 3700x/ 470x, Windows 11 with driver 22.8.2.

 
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So on both the AMD and Nvidia sides, what are the oldest cards that support Rebar?

AMD RX 5000 series and Nvidia RTX 3000 series?

No Rebar support on the old RX 500 cards right?
 
ZodaEX said:
So on both the AMD and Nvidia sides, what are the oldest cards that support Rebar?

AMD RX 5000 series and Nvidia RTX 3000 series?

No Rebar support on the old RX 500 cards right?
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For nvidia, only the rtx 3000 series has BAR, but that's why older amd and intel processors are supported, it seems to me even up to the intel 9000 series, if not older.
For SAM only amd processors from the 3000 series and only amd gpu from the rx 6000 series.
Apparently it can also work with the rx 5000 series, but you have to try it, no one has it anyway.
Intel and nvidia are the best in this, and amd is screwed again.
 
pendragon1 has a new amd cpu and an old amd gpu rx5700, he can confirm whether SAM works or not on rx 5000 series
 
b1rd said:
pendragon1 has a new amd cpu and an old amd gpu rx5700, he can confirm whether SAM works or not on rx 5000 series
Click to expand...

I'd never use a RX 5000 series anyway. It's TDP is too high. I'm much more interested in Rebar on a RX 550 or RX 560 card.
 
I have a 3700x with a 5700xt on a B550 never ran any testing but shows as being on.
 
What? My nvidia card does rebar on my X470 AMD board just fine.
 
Image Sharping is all that RX 500 got other then FSR 1 and 2.0 that I recall, I ran my RX 5700 with SAM on this same setup way before RX 6000 came out, I even tried my RX 5500 XT 8Gb before I sold it and SAM work on it also.
 
ZodaEX said:
Resizable bar has compatibility issues across vendors. AMD cards only do rebar on AMD chipsets and Nvidia/Intel cards only do rebar on Intel chipsets.
But who is at fault here for it not being universally compatible across all vendor's products? Is this Intel and Nvidia scratching each other's back, or is AMD also locking out Intel and Nvidia cards from using rebar on their platforms?
Click to expand...
Resize Bar is part of the PCIe Spec. It was a standard before anyone actually implemented it.

It doesn't "add" performance, well not exactly. In the HU video, when he shows graphs where there was no performance change with it off or on, those FPS results were always higher than the results from the same game where he was seeing differences with it off or on when using a diff gpu and/or cpu. He was bouncing between being CPU limited and being GPU limited. In the GPU limited graphs. no performance change was observed, and the performance was already good/maxed. So just a bit misleading when those situations, the performance is already higher than a different situation where Rebar was affecting performance... so implying it was or was not good was not actually being fair to resize bar. He was missing some obvious inferences.. He talked about a follow up video which never materialized as well.
In some cpu limited graphs there may or may not be an improvement. And the overall takeway was that it mainly helped in 1080p in cpu limited games, or when there was GPU power to spare. It feeds the GPU a little more efficiently for some games. That analysis could have been a lot more insightful and useful if he had compared fps in addition to just collating it into: here it helped here it didn't plus/minus graphs.
Because if the game is running in a cpu limited or gpu limited state, that effect combined with and without the resize bar feature would have been welcome information.

With what I gathered from the results, Rebar doesn't make any difference if you are gpu limited. It can help in old weaker systems with a powerful GPU installed. The irony being that most older systems have no Rebar support. So the analysis needs redone in 4 or so years, when the aged hardware might at least support it and it might contribute in a more consistent way.

It doesn't "add" performance, but can help get to available but suboptimally utilized GPU resources, in some cases, depending on the game engine. I suspect well written game engines will already have high efficiency in this regard which is why those games see no benefit.
 
GoodBoy said:
Resize Bar is part of the PCIe Spec. It was a standard before anyone actually implemented it.

It doesn't "add" performance, well not exactly. In the HU video, when he shows graphs where there was no performance change with it off or on, those FPS results were always higher than the results from the same game where he was seeing differences with it off or on when using a diff gpu and/or cpu. He was bouncing between being CPU limited and being GPU limited. In the GPU limited graphs. no performance change was observed, and the performance was already good/maxed. So just a bit misleading when those situations, the performance is already higher than a different situation where Rebar was affecting performance... so implying it was or was not good was not actually being fair to resize bar. He was missing some obvious inferences.. He talked about a follow up video which never materialized as well.
In some cpu limited graphs there may or may not be an improvement. And the overall takeway was that it mainly helped in 1080p in cpu limited games, or when there was GPU power to spare. It feeds the GPU a little more efficiently for some games. That analysis could have been a lot more insightful and useful if he had compared fps in addition to just collating it into: here it helped here it didn't plus/minus graphs.
Because if the game is running in a cpu limited or gpu limited state, that effect combined with and without the resize bar feature would have been welcome information.

With what I gathered from the results, Rebar doesn't make any difference if you are gpu limited. It can help in old weaker systems with a powerful GPU installed. The irony being that most older systems have no Rebar support. So the analysis needs redone in 4 or so years, when the aged hardware might at least support it and it might contribute in a more consistent way.

It doesn't "add" performance, but can help get to available but suboptimally utilized GPU resources, in some cases, depending on the game engine. I suspect well written game engines will already have high efficiency in this regard which is why those games see no benefit.
Click to expand...

HU video? What's a HU?
 
It's more about the cpu getting a bigger pathway (256Mb) limit to the video card memory and not use or need as much slower pathway system memory, kind how I took it.
 
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ZodaEX said:
HU video? What's a HU?
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1663846828663.png
 
Mchart said:
What? My nvidia card does rebar on my X470 AMD board just fine.
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I just needed to turn it on in the mobo bios with my RTX3070 / x470 / 5700x setup I got going on now, Nvidia system info says it is on with windows 11, crazy thing about the mother board was buying it from newegg in 2019 for $75 refurbished and using a 2200g to flash it to Ryzen 3000, best board that I ever bought for price and now it doing Ryzen 5000.
 
No issues with rebar on my 5900x/3080 combo.

But then again, I haven't really tested performance with it toggled being off either.

Should I?
 
For the guys on older systems, make sure to update your windows bios from Legacy to UEFI. I updated MB bios, 3070 firmware, and turned on rebar in bios. Nvidia info still said NO and I realized the problem was that I was still on legacy.
 
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